1. Field of the Invention
This invention relates generally to electronic file protection, and more particularly to electronic file protection using location and other entropy factors.
2. Description of the Related Art
The use of public and private networks has fundamentally altered the manner in which business enterprises and government agencies communicate and conduct business. For example, the Internet, intranets and extranets are used to store, analyze and transmit information between and within organizations, and permit interactive, local, national or global communication on a real-time basis. Moreover, these networks are now used for electronic business-to-customer retail commerce and for electronic business-to-business commerce of all types.
Electronic files today are easily copied and transmitted widely throughout the world in a largely uncontrolled and nearly instantaneous fashion. Multiple computers connected through a variety of local and global networks can share information through the copying and electronic delivery of files. Further, a variety of tools have been developed to facilitate file sharing and communication, such as Virtual Private Networks (“VPN's”), Peer to Peer (“P2P”) software, various instant messaging packages as well as others. Due to the wide availability of this software, computer files of all types are shared with increasing frequency. Moreover, the continuing reduction in the price of storage devices such as disk drives further encourages this activity, since the cost of local storage does not suppress the benefit obtained by having immediate and continual access to the data.
As a result, there is a strong and pressing need for a complete solution to the protection of copyrighted information in this electronic environment. Owners of copyrighted digital data, such as video files, audio files and reports, are very concerned about the proliferation of world wide sharing of files, since this often constitutes a direct violation of copyright laws and leads to the erosion of revenue due the owner. Some sharing engines caused such concern about copyright infringement that legal battles have risen to the highest courts in the land in an attempt by copyright owners of audio data to control the distribution of their material.
Several software solutions have been developed to attempt to address the problem of unauthorized duplication of electronic files, but these solutions are inadequate. Techniques such as strong encryption, digital watermarks and other forms of unique identification or access control are necessary but not sufficient protection of copyrighted material, as is evidenced by the fact that owners of copyrighted material have been very reluctant to offer their material over electronic distribution channels such as the Internet.
Digital watermarks imbed hidden information in a copyrighted file so that ownership can be demonstrated whenever a file with the watermark appears. Some implementations of the technology scramble the file so that it is not usable until unlocked by an authorized key. Keys, however, can be distributed just as easily as the source files, thereby neutering any protection afforded by the watermarking technology. Other solutions hide the watermark and require that the copyright owner “police” his property through the identification of illegal copies as they are found. The onus remains with the owner to enforce his ownership through legal prosecution of the person(s) holding the illegal copy. Still other implementations offer a “reduced function” access to the file (e.g., degraded audio performance so that a user may listen to the file before purchasing it) until the user purchases a license to the copyrighted material. The owner may further attempt to stem his losses by tracking the transmission trail of the document, although tools for such tracking are inadequate or missing entirely.
The reluctance of the owners of copyrighted information to migrate to electronic distribution or delivery of their material using digital watermarking is easily understood. Digital watermarking does not prevent the distribution of electronic material, but rather places the burden upon the owner to locate and then prosecute people holding illegal copies. The lack of tools to track the distribution path by which these copies were transmitted does not provide any assurances that such distribution will be stemmed by the prosecution activity. The ease with which keys can be distributed or posted in newsgroups gives further pause to copyright owners. Hence, a solution is needed in which copyrighted materials can be transmitted to an authorized purchaser with confidence that the file cannot be distributed in any usable fashion.
To address this issue, a variety of very strong encryption technologies have been developed over time. The strongest of the encryption technologies, public key encryption, employs dual-key systems in which each party has a public key that is widely distributed, and a private key that is kept secret to the user on his machine. Specifically, using public key infrastructure (“PKI”) encryption, digital messages are encrypted and decrypted using ciphers or keys. FIG. 1 is an illustration showing a conventional public and private key pair 100. The public and private key pair includes a public key 102 and a private key 104. Each user of the system has a public key 102 and a private key 104 and must know the public key 102 of the intended recipients of its messages. In general, a message is encrypted and sent by a sender using the recipient's public key 102 and is then received and decoded by the recipient using his private key 104, as discussed in greater detail next.
FIG. 2 is an illustration of a conventional PKI system 200. In FIG. 2, two network computer users, Alice 202 and Bob 204, each have their own public and private key pair. Specifically, Alice 202 has a public and private key pair comprising a public key 206 and a private key 208. Similarly, Bob 204 has a public and private key pair comprising a public key 210 and a private key 212. The private keys 208 and 212 are secret numbers to which only the owner has access. In general each public key is generated using the following formula:(1) GxmodP,
where G and P are large prime numbers and x is the user's private key. In this manner, eavesdroppers would have great difficulty determining x even if the values of G and P are known. Hence, the public keys 206 and 210 can be broadly disseminated without revealing the related private key. For example, Bob 204 and Alice 202 provide their public keys 210 and 206 to each other prior to initiation of encrypted communication.
Thereafter, whenever encrypted communication is to occur, the sender utilizes their private key in conjunction with the recipient's public key to encrypt the data being sent. Upon receipt, the recipient decrypts the data using the recipient's private key. For example, when Alice 202 wishes to send Bob 204 an encrypted message, Alice 202 encrypts the message using her private key 208 in conjunction with Bob's public key 210. Upon receipt, Bob decrypts the message using his private key 212.
PKI systems attempt to provide a high level of security and confidentiality because messages can be decoded only by persons having the recipient's private key. However, it is well known in the industry that a weakness of PKI technology is its susceptibility to the “man-in-the-middle” attack.
FIG. 3 is an illustration showing a PKI system 300 compromised by a middleman. In particular, FIG. 3 illustrates three network computer users, Alice 202, Bob 204, and Cindy 302, who in this example is the middleman. As in FIG. 2, Alice 202 has a public and private key pair comprising public key 206 and private key 208, and Bob 204 has a public and private key pair comprising public key 210 and private key 212. In addition, Cindy 302, the middleman, has a public and private key pair comprising public key 304 and private key 306. If Cindy 302 can intercept a transmission between Bob 204 and Alice 202, she can trick them into using her public key 304. In this attack, the attacker intercepts the transmission of a public key and replaces it with the attacker's false key, thereby effectively replacing the true sender as the trusted party. This enables the attacker to send, receive and decode messages intended for the original legitimate user.
For example, during a “man-in-the-middle” attack, Cindy 302 intercepts Alice's public key 206 and replaces it with Cindy's public key 304. Similarly, Cindy 302 intercepts Bob's public key 210 and replaces it with Cindy's public key 304. Bob 204 and Alice 202 each believe they have each other's public key, however, they actually have Cindy's public key 304. Later, during encrypted transmissions, both Alice 202 and Bob 204 unknowingly use Cindy's public key 304 in conjunction with their respective private keys to encrypt messages to each other, Which are actually intercepted by Cindy 302. Cindy 302 can decrypt the messages using her private key 306, and further, re-encrypt the messages using Cindy's private key 304 and the proper recipient's public key 206 and 210.
As deployed today, public key encryption cannot and does not have any means to authenticate the identities of either party involved in a transmission. The parties must rely upon trust or some other means of authentication in order to be certain that the identity of the other party is indeed the person with who they wish to communicate.
The strength of this public key encryption technology is state of the art today, with legendary estimates of the time and processing power required to crack a public key encrypted file. One estimate, for example, suggests that a file encrypted using moderate strength public key encryption would require all of the computers in the world working together for one year in order to decrypt the file without the benefit of the required secret key.
Although strong encryption provides protection of copyrighted material against decryption without the required secret key, there is no protection against the distribution of the secret key or the distribution of the file once the purchaser has decrypted it. Even if used in conjunction with digital watermarking technology, the daunting task required of the copyright owner to seek and prosecute violators of the copyright material creates a significant inhibition against migrating the distribution of copyrighted material to the electronic world.
A number of attempts have been made to increase system security in the prior art. The following is a list of prior art disclosures that provide some form of file security. However, as will be seen, none of the disclosures provides a level of security currently needed to ensure proper protection of today's highly sensitive data.
In U.S. Pat. No. 4,993,067, Leopold discloses a process by which location is used to reset a decryption key of a remote user. In this process, a user transmits a request for a new key to a communications satellite. The satellite then determines whether the location of the source is authorized. If so, it then sends instructions to the remote source for re-keying its decryption software. The system requires that the remote user be stationary, and that the satellite itself carry a location filter that blocks signals from non-authorized locations. This is practical only for application specific satellites and does not provide a means for authentication of the user's location.
In U.S. Pat. No. 5,343,529, Goldfine et. al. describe a system by which a user requesting access to data presents such a request to a server. The server then transmits a session-specific userid to the user, and simultaneously calculates a hash code based on that userid. The user calculates a hash code based on a pre-determined algorithm, and sends the code back to the server. If the two hash codes match, the user is considered authentic and access is allowed. The security of this system is only as good as the secrecy of the predetermined algorithm (static entropy), and does not employ location or dynamic entropy to further authenticate the user.
In U.S. Pat. No. 5,640,452, Murphy describes a system by which a receiver that receives encrypted television transmissions will only operate within a physical range around its pre-set location. The system employs a GPS receiver operating in close proximity to the receiving antenna. If the current location as received by the GPS unit is within an acceptable range of coordinates that have been stored within the antenna's local electronics, the circuitry sends an enabling pulse to a decryption chip which then decodes the received transmissions. The system is susceptible to short-circuiting the enabling line to enable the decryption chip at all times and failure of the GPS unit. Moreover, it does not involve a challenge/response process for authentication of the user or his location, nor does it employ dynamic entropy for enhanced security.
In view of the forgoing, there is a need for systems and methods that provide self-protecting electronic files. The self-protecting electronic files should protect themselves based on a set of variables defined by the copyright owner at the time of authentication and downloading. Furthermore, the file protection should preferably include location information that can be independently certified. Location information alone, although valuable, is not sufficient. Thus, the location should be authenticated to significantly reduce any possibility of location spoofing.